"There is nothing. We went there, there is nothing," he told the Associated Press.

Vietnamese officials previously said the area had already been "searched thoroughly" in recent days, the AP reports.

Meanwhile, U.S. investigators believe the missing jetliner flew on for four hours once it lost contact with air traffic controllers, The Wall Street Journal reports.

Their theory is based on data from the plane's engines that are automatically downloaded and transmitted to the ground as part of routine maintenance programs.

The images captured by Chinese satellites, taken Sunday, show three fragments in the South China Sea between Malaysia and Vietnam, in an area near its intended flight path. They were posted Wednesday on the website of China's State Administration of Science, Technology and Industry for National Defense.

Beijing-bound Flight 370, with 239 people aboard, vanished about an hour after it took off from Kuala Lumpur International Airport. Its final transmission indicated no problems just minutes before it disappeared over the South China Sea, south of Vietnam's Ca Mau peninsula.

Li Jiaxiang, chief of China's Civil Aviation Administration, said Thursday that his agency cannot confirm the objects in the Chinese satellite images are from the missing aircraft.

China's delay in releasing the images, taken Sunday but released only Wednesday, and the apparent failure to provide them directly to Malaysian authorities, raises serious questions about cooperation between Beijing and Kuala Lumpur.

Rahman, said Thursday that Malaysia had not been officially informed by China about the satellite images of possible debris, which he said he learned about from the news, reported the Associated Press. If Beijing informs them of the coordinates, Malaysia will dispatch vessels and planes immediately, he said, according to AP, with the caution that "there have been lots of reports of suspected debris."

China's state-run media have been critical of Malaysia's handling of the crisis, and its foreign ministry spokesman Qin Gang complained that "There's too much information and confusion right now. It is very hard for us to decide whether a given piece of information is accurate."

At a meeting in Beijing Wednesday between Chinese and Malaysian officials, the Chinese side "requested the Malaysian government as well as Malaysia Airlines to release authorized information in a timely manner, update the latest progress of their work, respond to doubts and appeals of the passengers' relatives, and console the relatives and the public," China's official Xinhua News Agency reported.

Some Malaysians now doubt both their national carrier and the country's ability to deal with the search and investigation.

"They always say everything is tip-top, the pilots are the best, the planes are the best, but maybe it is not as great as they say," said Siti Paridah, 60, a housekeeper in Kuala Lumpur.

"I think the government is trying its best, non-stop, but for relatives the search seems too slow. They are so anxious. It's been over five days now and nothing materializes," said Siti Paridah, who knows a family in her home village still awaiting news of their son, who was on the missing flight.

"Maybe it is too hard for Malaysia. In this situation, we do not have experience and it is a large area to search," she said.

Malaysia doubled the size of the search area for the airliner after releasing the last words radioed by the Boeing 777: "All right, good night."

The words from someone in the cockpit were picked up by air traffic controllers early Saturday and provided to relatives of some of the passengers in Beijing Wednesday.

The search for the missing plane was expanded to 35,800 square miles of Southeast Asia ocean that now includes part of the Indian Ocean.

A Malaysia military radar indicated an unidentified plane was in the air hundreds of miles west of Flight 370's last recorded position about one hour after it vanished. That would've put Flight 370 well off course, but it is not known if the radar was accurate.

Still, Malaysia moved additional search and rescue assets to the Straits of Malacca in case, said Gen. Seri Zulkifli Mohdzin, Malaysia's chief of armed forces.

Acting Transport Minister Hishammuddin Hussein defended the government's handling of the disappearance. "Our information is consistent, it's transparent, we have nothing to hide," he said.

In Shenyang, Zhao Wenjing, 28, whose husband is a Chinese domestic airline pilot, said she had mixed feelings about the search and Chinese satellite images of possible crash debris.

"On one hand, I am eager to know where the plane is,'' she said. "On the other hand, I wish there is no news. Then we still have hope.''

The confusion upsets relatives of the missing passengers, especially in China, home to the majority of passengers.

"There is much contradictory news, I really don't know what to believe, I am waiting anxiously with my family relatives," said Zhang Hongjie, a Beijinger whose wife was on the flight after a holiday in Malaysia.

The military radar indicated a plane was flying 200 miles northwest of Penang at 2:15 a.m. Saturday morning, said Malaysia air force chief Gen. Rodzali Daud. The data indicate a "possible turn back" from the expected flight path of Flight 370, he told an evening press briefing.

Authorities are working with the U.S. Federal Aviation Administration and the U.S. National Transportation Safety Board to confirm if the plane is the missing MH370. To pinpoint the plane's last location, U.S. experts will assist Malaysian officials in analyzing both civilian and military data.

The last civilian radar data ended at 1:30 a.m., on the east side of the peninsula, said the country's civilian aviation chief, Rahman. The physical search involves 42 ships and 39 aircraft, said Hishammuddin.

Malaysia Airlines has offered Chinese families of the missing a $5,000 "condolence" payment they say is not related to compensation. Some relatives have rejected the payment, but Zhang said he would probably accept.

If the plane is found, Zhang will travel to the location. Malaysia Airlines has already flown some family members to Kuala Lumpur, where they await news in a suburban hotel. The limit per family was set at two, but Zhang has five family members who want to go, including the couple's 18 year-old daughter. Concerned about the painful purpose of the journey, Zhang has not yet decided if the girl should accompany him, he said Wednesday.

In Beijing, efforts continue to offer comfort to the relatives gathered in three hotels. "The relatives are very upset and in pain, we offered them help such as translation, snacks and drinks, and asked people in sorrow to think positively," said Zeng Yunji, 53, a volunteer for the Taiwan Compassion Relief Tzu-Chi Foundation, a Buddhist charity.

"We told them, everything is not clear now, let's hope for the best," said Zeng, who cheered one weeping woman, whose husband is missing, by encouraging her to pray in her heart and repeat over and over, to her husband, "you must come back safely."

The charity's volunteers include Buddhists, Christians, Catholics and Muslims, she said. "Religion has power, but you don't have to believe to have influence, we all have a kind heart, that's what we share," said Zeng. "We will stay here until all the relatives have left."

Authorities in Malaysia appear to be working hard to get results they can verify and release. The confusion has followed contradictory statements by some of the multiple government agencies and the Malaysian military, working together with several Asian neighbors and the U.S. Navy, involved in the search for the plane and investigation into its disappearance.

With the world's attention on their country, some Malaysians wish the government would find a better public communicator to run the packed daily press briefings. "The quality and competency of the officials involved are somewhat lacking," Tan Eng Bee wrote in a letter published Wednesday in the New Straits Times newspaper.

Correction: An earlier version had the names of the Federal Aviation Administration and the National Transportation Safety Board wrong.